Device-to-device (D2D) communication generally refers to a communication in which user data can be transmitted directly between terminals without being relayed via a network. D2D communication can reduce a load of a base station and can remedy the defect that cellular devices outside of the coverage of the base station cannot communicate effectively.
D2D communication can be applied to various scenarios. For example, traffic data of user plane may be directly transmitted locally without transmitting via network side, to offload a cellular network traffic, for example; wireless communication between terminals are ensured with the D2D communication in a case where a natural catastrophe occurs and traditional communication network infrastructures are damaged; and D2D communication enhanced for the Internet of Things, etc.